Method and system for producing a potential over a body

ABSTRACT

This application concerns a method and system using a hydrodynamical effect for producing a potential over a body. The force obtained this way is useful for the propulsion and maneuvering of ships, submarines, aeroplanes, and airships. A body immersed in a fluid at rest is subject to equal pressures on all sides. A stream close to one side of the body will reduce the local pressure and produce a potential over the body. This is currently done by moving the body in the fluid, cf. aeroplane wings. The potential may be produced by setting up a stream or streams over one side of the body. Bodies attached to aeroplanes by hinges are useful for their lift, propulsion and maneuvering, and will make them independent of velocity for lift and maneuvering. The same will be the case for submarines. Airships and seagoing vessels may be designed so as to have their propulsive bodies integrated in their form. The streams are produced from nozzles, holes, or slits in tubes placed near the stagnation line of each body, thus defining its leading edge. Used on a ship, this technique lowers its bow wave and removes the dynamical losses connected with screw propulsion. The maneuvering force and precision are enhanced.

This application concerns a method and system using a hydrodynamicaleffect for producing a potential over a body. The force obtained thisway is useful for the propulsion and maneuvering of ships, submarines,aeroplanes, and airships.

I. General.

Hydrodynamics concerns the relation of forces between a stream of fluidand its neighbouring fluid or body. A stream will transmit a forceaccording to its velocity and mass density.

In a stream or at its periphery, the pressure is reduced so that thetotal energy of the stream and its ambient fluid is unaltered. Thisprinciple was described by D. Bernoulli (1).

The energy of a stream is equivalent to the potential of a staticpressure differential. The pressure is measured in pascal; and theenergy of the stream is ½ ρv², also Pa. Their equivalence is seen inPa=Nm⁻²=Jm⁻³=W/m³s⁻¹. The hydrodynamical effect is a function of themass density of the fluid and the square of its velocity.

A stream may be seen as a pressure vector. From it, a pressuredifferential is transmitted normally to the direction of the stream,producing a force, cf. ∇×E=−∂B/∂t (J. C. Maxwell). A measure of theenergy exchange of the vector is taken as the integral of theinteraction over a given time.

The hydrodynamical principle is distinguished from the kinetic principledescribed in Newton's three laws. In the use of fluid mechanics fortechnical applications, the different nature of these two principlesshould be kept in mind, as they set different constraints and lead todifferent technical consequences. The physical functions and technicaldetails of kinetic technology should be kept conceptually apart fromeach other, and from those of hydrodynamical technology.

The force obtained by a reaction device is the product of an acceleratedmass: F=m·a, or the product of the quantity of mass per unit of time andits velocity: F=m.t⁻¹·v.

The force obtained by the pressure differential of a stream is thedifference of pressure relative to the undisturbed fluid times the areaof the surface over which it works. Here, the mass density p of thefluid is a factor: F=Δp·A; or F=½ρ·v².A. The hydrodynamical force is afunction of the square of velocity of the stream.

Oars and caudal fins are reaction devices. For the tecnical use of fluidkinetics, an axially mounted reaction device is needed in order toabsorb the propulsive momentum. It will be a propeller, rocket, nozzle,or jet engine.

Where a stream is used for producing a momentum by reducing the pressureof its ambient fluid, it is not useful for producing a reactive force,as the directions of those two are normal to each other.

The lifting force of an aeroplane wing is produced by its splitting themeeting air and thus setting up two streams by its movement. As thestreams follow the two sides of the wing, they get different courses andvelocities. The wing is lifted by the differential of the transversalforces of the streams, which, because of the speed of the aeroplane, isa relatively small differential of considerably reduced pressure, as thepressure side and the suction side are both exposed to a high airvelocity.

A part of the lifting force of the wing is kinetic, produced by thevertical component of the stream induced by the angle of attack of thewing, cf. the sinking of a glider.

Passenger aeroplanes illustrate the lower need for power in thetechnical use of hydrodynamics compared to that of kinetics. At thestart, their propulsive force is around 40 per cent of what would havebeen needed as a vertical reactive force in order to lift the aeroplaneagainst the acceleration of gravity, cf. Newton's third law. Cruising ata height of 11,000 m, the propulsive force of the aeroplane equals lessthan 25 per cent of the vertical reactive force needed. This does notimply that Newton's third law be invalidated. Hydrodynamics is, though,not what it is intended to describe. Hydrodynamical forces are notadequately described nor calculated within the models belonging to thekinetic part of fluid mechanics.

The force obtained by this principle used in the present technique iscurrently calculated by the circulation model, as the reactive force tothe centripetal force mv²/R, or by the equation describing the principleof Bernoulli. These three are models, i.e. tools for calculation, whileBernoulli's equation is also a theory, i.e. a postulate concerningspecific properties of reality.

The principle is referred to in a Norwegian application for patent (3);and it is the functional principle of a patented device (8). Inpractised technology, it constitutes a part of the function of aeroplanewings.

The application of this principle is known from an experiment with thepurpose of augmenting the lift of aeroplanes at low speed. Using anoblong nozzle, an added stream was drawn in between the nozzle and thesurface blown. Compared to the reactive force of the stream, a thrustaugmentation of 1-37 was attained (5). This device is, however, notoptimal, as a higher efficiency is achieved when the stream has itshighest velocity close to the surface, cf. the aeroplane wing. By thesame way of calculation, a passenger aeroplane has a thrust augmentationof 2-5-4.

An optimal conversion of energy for a technical purpose presupposes thatthe different functions of the physical variables are separated withinthe apparatus. This is what is seen in Watt's placing the condenseroutside the cylinder of the steam engine; and it is the principleapplied when the pressure of an combustion motor is converted through apump into pressure in a fluid.

Instead of producing the stream differential passively by moving thebody in the fluid, it is possible to produce it actively by moving thefluid over the body. It is then possible to produce the potential bysetting up a stream over one side of the body only. In this lies thereason for applying the hydrodynamical principle to marine purposes andfor designing aeroplanes having other properties than those of theaeroplanes presently used.

The water around a ship at rest is in a hydrostatic equilibrium. Thewater pressure is equal to an energetic potential: Pa=Nm⁻²=Jm⁻³. Thestatic pressure at a given depth is constant. Any manipulation of staticpressure in a fluid in the open must be indirect, by a change of thedynamical pressure. Technically, this takes place by introducing streamsof water. In aeroplanes and airships, streams of air are used.

A stream or streams close to the vessel will disturb the equilibrium byreducing the local static presssure to a level calculable by Bernoulli'sequation. This is equivalent to reducing the local force over the partof the surface of the vessel flushed by the streams, thus releasing thelocal potential of the adjacent fluid.

In combination with the undisturbed pressure on the opposite side of thevessel, sustained streams will produce a differential of pressurerelative to the potential. This differential will release its potentialby imparting a momentum to the vessel.

This hydrodynamically produced momentum is directed normally to thedirection of the streams. It is useful for lift and propulsion.

When the body moves, the velocity over its opposite side, the one thatis not flushed, will produce a reduced pressure and an accompanyingforce. As long as this pressure reduction is not as great as the ambientpressure, there will be a net force pushing the body.

The system here described is a simple apparatus which produces atechnical effect by producing a pressure differential in the ambientfluid of a vessel, thus releasing a part of its potential and malting ituseful for lift or propulsion. It is not possible to refer to anypublished empirical or theoretical foundation for a calculation of itsdistribution of energy in the fluid, its forces, or its effects. Amongthe references are works having a general relevance for hydrodynamicaltechnology (4, 7). Other relevant information will be found in textbooksof advanced studies, e.g. marine hydrodynamics, rotating machines andthermodynamics.

I. Special.

The present invention relates to a method and system for producing apressure differential over a body by actively flushing one or more sidesof the body, thereby establishing a low pressure region. The pressuredifferential is thus created between the low pressure region and theopposite side of the body.

From the apparatus described in ref. 5 it is not possible to derive thesystem described here. This is derived indirectly from what is seen tobe principles of fluid mechanics at work in current technology, likeaeroplane wings, propellers, pumps, and turbines. To the principlesobserved have been added the distinctive traits of rotatable tubes andclose flushing.

The effect of the flushing is a reduced pressure over a surface. Inconjunction with the pressure over the opposite side of the body, thisexposes it to a force, useful for lift. A sustained flushing produces amomentum, useful for propulsion and manceuvering. As seen above, thismethod is better than reactive devices for producing a force.

The air velocity difference over an aeroplane wing is 5-10 per cent. Aslong as the aeroplane velocity is above a threshold, the hydrodynamicalpotential of the velocity difference over the aeroplane wing will, asshown above, be more power efficient for producing lift than a reactiveforce can be.

A technically produced stream according to the method presented herewill have its velocity limited to that of sound, even for rather slowaeroplanes. Thus, it will be possible to produce a greater specificlift. Within this constraint, the lifting force will depend upon thepower used and will permit competitive velocities of aeroplanes.

By inclining the lifting body forward, it is used for propulsion andlift simultaneously. As the efficiency of jet engines is not remarkablyhigh, propulsion by the horizontal vector of an inclined, flushed,lifting body will be more efficient. This will permit slow and low-goingaeroplanes. The advantages of manceuvering by longitudinally andtransversally inclinable bodies will be great, combining the versatilityof the helicopter with the smaller engine installation needed forhydrodynamical lift and propulsion.

Friction and viscous resistance over the immersed surface are present atevery contact between streams and surfaces, so are inavoidable invessels.

Two other components of resistance are seen at towing a ship: anelevated pressure fore and a reduced pressure aft. By the use of apropeller, which draws water before accelerating it through its disk,the pressure around the stem is even more reduced, producing a forceagainst the forward motion of the ship. Ahead, the bow wave signals anincreased pressure, which is the energy needed in order to remove thewater from the course of the ship.

These two components, the bow wave and the thrust deduction fraction,are currently seen as dynamical resistance bound to the propulsion ofships. Together, they consume 30-45 per cent of the shaft power in mostships (2, 6).

They may as well be seen as generic technical losses induced by thepropeller. Except a part of the reduced pressure aft, they are not boundto ship's propulsion as such.

The present state of ships' propulsion is one of suboptimization, as theuse of the reactive force of a propeller confers a series of constraintsto the form and performance of ships. These are taken to be theconditions of ships' propulsion as such, cf. the relevant literature,e.g. ref. 2 and 6. The models for calculating power, velocity, andpropellers' presumed optimal properties, are empirical and have atenuous connection to physics. In order to predict the performance of aship, a model of it is tried; and it has to be of a certain size inorder for the impreciseness of the scaling factors to be overcome.

The propeller itself is a suboptimal reaction apparatus. On the basis ofphysical functions, it has been possible to design an optimal propeller(9). It will not, however, reduce the two components of resistance boundto reactive propulsion.

The same relation as for aeroplanes between power applied and momentum(or first moment of mass) produced is valid for any body moved in afluid or held against the acceleration of gravity. The hydrodynamicallyproduced force is more power efficient than a reactive force; and itputs fewer constraints on design and performance of the vessels.

For ships, the pressure differential generating stream will have avelocity of more than twice the velocity of the ship. By flushing thebow, the force generated by the pressure differential between it and thelongitudinal projection of the after ship will be higher than thatobtainable by a propeller, since the surfaces involved are greater. Thismoving force is produced without an inherent loss of efficiency likethat of a propeller, cf. the turbulence of the propeller race.

By this technique, the ship is made into its own propulsive contrivance.

A known way of producing streams over a ship's bow is to use nozzles(3). A technically more efficient way is to place the nozzles in thewalls of two pressure vessels formed like tubes at or near thestagnation line of the surface of the body over which the pressure is tobe reduced. By the use of a string of nozzles in each tube, thestreaming fluid is distributed over this surface. By malting the tubesrotatable, the reactive force of the streams will be useful for brakingand steering, which can be performed simultaneously. Braking will bepossible even with large vessels.

On seagoing vessels, the two tubes are placed on the middle of the bowso as to distribute the streams over its curved surfaces, as it isformed like one vertical, circular semi-cylinder or like two verticalsemi-cylinders having an adequate cut for the purpose of the ship. Theposition of tubes defines the leading edge of these two sectionsurfaces. The aft longitudinal projection of the ship defines thepressure side.

The tubes are protected by a vertical body ahead so that the streamdiverted by it will meet the bow at or near the lines where the flushingstreams meet the bow.

Ships and ferries with a need for precise manceuvering will have theirstern formed like the bow. Tubes with nozzles are fittedcorrespondingly. Braking is performed by rotating the tubes ahead 90° orby flushing aft.

On aeroplanes, curved surfaces or movable bodies with one curved surfaceare flushed with air streams from tubes placed near their stagnationlines. In order to prevent the meeting stream from following thepressure side of a movable body, a plate is hinged to its leading edgeand prevented from fluttering by the aid of shock absorbers.

The force generated by the pressure differential is useful for lift,propulsion, and manceuvering. On aeroplanes, the last two are obtainedby inclining the hinged bodies axially and transversally, thus usingboth the vertical and the horizontal components of the vector of thepotential.

A ship may be interpreted as two wings put together, so that theirsuction sides form the bow and the sides of the ship, cf. the drawing.The part of a ship corresponding to the pressure side of a wing will bethe aft longitudinal projection of the ship.

This method will bring a series of advantages:

Aeroplanes can be made small, with a fuller body, and nearly noiseless.

The transversal forces of a ship or an aeroplane will be considerablygreater than those obtainable by a rudder, making possible an efficientsteering.

Aeroplanes will be made to hover, brake in the air, fly in narrowcurves, turn on the spot, fly sideways, and land or take off verticallyfrom a small ground. The aeroplane will easily be kept in an uprightposition.

The need for power will be considerably lower than in helicopters.

In a ship, the efficiency of sideways translation in combination with orindependent of longitudinal movement will be higher than that oftransversally working propellers, as it may be performed by the wholepower of the prime mover.

With nozzles fore and aft, it will be possible to translate the wholeship sideways (sway) and to rotate it on the spot (yaw).

A precise steering will make easier the passage of rivers, straits, andcanals. It will be possible to follow a precise course without pushingthe stern out the way it is by the use of a rudder. Coasters will beable to maneuver without swaying and to go fast even in narrow waters.

Since the bow wave will be insignificant, there will be a low wash,making possible the passage of rivers, straits, and canals at higherspeeds without damage to shores or small craft.

The system may be used on full ships, which will have a smaller wettedsurface and a smaller steel weight relative to their volume. It will bepossible to use form coefficients that are inapplicable today. It willalso be possible to design a ship of smaller draught relative to itsdeck area or to its volume and dead weight.

With diesel-electrical propulsion or fuel cells, an optimal use of aship's volume will be possible.

The system is built on known technology. Centrifugal pumps are used atsea, thus water nozzles are the only new part of the propulsion system.Removing of particles from pump circuits is routine at sea. The systemwill be easily maintained.

There will be no risk of overloading motor or pump.

The system renders a high degree of security. Tubes and nozzles are lesseasily damaged than propellers are, as they are not protruding normoving appendages.

It will be possible to isolate engines and pumps from the hull. Thiswill impede the propagation of motor noise and vibrations in the ship.

There will be no vibrations like those generated in the stern by thepressure differences from the propeller. The nozzles will not generateany low-frequency energy, but produce high-frequency sound only, whichis of short range, as it is quickly damped in water.

It will be possible to reduce the quay erosion which is sometimes aproblem in the ferry trade, as its possible to brake aft on arriving atthe quay. At departure, the double-ended ferry is flushed at the foreend.

Since most ferry quays are open on one side, the use of catamarans willbe possible. These will have an advantageous relation betweendisplacement, draught, capacity, and speed. Two bow gates in each endwill make possible the use of existing ferry quays.

Submarines may be directed downwards along a steeper angle than that nowpossible by the horizontal rudder alone.

REFERENCES

-   -   Daniel Bernoulli: Hydrodynamica, 1738.    -   Sv. Aa. Harvald: Resistance and Propulsion of Ships, John Wiley        & Sons, New York, 1983.    -   Arne Kristiansen: Norwegian application for patent n^(o)        19905214.    -   B. S. Massey: Mechanics of fluids, 2^(nd) edition, Van Nostrand        Reinhold, London, 1970.    -   T. Mehus: An experimental investigation into the shape of        thrust-augmenting surfaces in conjunction with Coanda-deflected        jet sheets, University of Toronto, 1965.    -   Harald Walderhaug Motstand og frarndrift, Institutt for marin        hydrodynamikk, 1988.    -   S. W. Yuan: Foundations of fluid mechanics, 2^(nd) edition,        Prentice-Hall International, London, 1970.    -   Jan Inge Eielsen, Fluma A S: Norwegian patent n^(o) 305796.    -   Arne Kristiansen: Norwegian patent n^(o) 143093.

1. A method for propelling and maneuvering a body having a curvedleading edge through a fluid, comprising the steps of: a) providing oneor more nozzles that eject one or more streams of pressurized fluid b)directing the pressurized stream or streams that exit from the one ormore nozzles towards the surface of the body at the leading edge, at anangle and velocity sufficient to generate a pressure potential betweenthe leading edge and trailing edge, the pressure potential being of amagnitude sufficient to impart movement of the body through the fluid.2. The method of claim 1, wherein a plurality of nozzles are integratedin a rotatable cylinder mounted to the leading edge of the body.
 3. Themethod of claim 2, wherein the body is a seagoing vessel, the fluid iswater, and the curved leading edge is the bow of the vessel.
 4. Themethod of claim 3, wherein the nozzles are arranged to eject a pluralityof pressurized streams directly against the surface of each side of thevessel at a point at the immediate vicinity of the front of the bow. 5.The method of claim 3, wherein the angle of the pressurized streams maybe selectively adjusted in order to propel, steer and brake the vessel.